1. Field of the Invention
This invention relates generally to a light-ray indicator, and particularly to apparatus for automatically indicating a point perpendicular to or horizontally from a predetermined point.
2. Description of the Prior Art
It is known to project a light beam aligned along a plumb line for transferring markings from one point to another on the plumb line. Devices employing this concept, an example of which can be found in U.S. Pat. No. 3,858,984, issued Jan. 7, 1975, to H. M. Denton, et al., usually have a lamp mounted on a support by a universal joint, and a weight functioning as a plumb bob attached to the lamp for aligning same along a plumb line. U.S. Pat. No. 3,858,984 also shows an adaptor unit which permits the light beam to be projected horizontally for performing surveying and similar functions.
It also is generally known to provide transits with laser beam projecting devices, examples of which can be found in U.S. Pat. Nos. 3,469,919, issued Sept. 30, 1969, to F. L. Zellner, and 3,471,234, issued Oct. 7, 1969, to R. H. Studebaker, while U.S. Pat. No. 3,635,565, issued Jan. 18, 1972, to G. P. Colson, discloses a laser vertical collimator which establishes a plumb reference line for use in construction of buildings or shafts.
A fundemental problem encountered with employing a laser beam as the light source in a light-ray indicator is that laser emitting sources require amounts of power far in excess than that which can be contained in a housing universally mounted on a support in the manner disclosed in the aforementioned U.S. Pat. No. 3,858,984. Accordingly, it is necessary to connect the laser tube or other suitable laser source contained within the universally mounted housing with a power supply located externally of the housing and its associated universal mounting.